It gets complex, but the big picture is that these nations are still at war with us on their terms, and have been for a long time.
No nation has been at war with the US longer than Russia. England would normally occupy that slot, but they became dependent on the US by the time of the Great War, and we out-paced them dramatically in finance, military, and naval power so that they then had to hitch their wagon to ours for long-term viability once the Empires were all defeated after 2 World Wars.
Russia recognized all this, but allowed its Czar to be overthrown and its nationalist people to be mass-murdered by Bolshevik demons for decades, then lost 20 million people in what they call The Great Patriotic War.
The US represented a threat to Russia even before the Soviet times, because we proved that a government could exist without authoritarian rule by a king, dictator, or Czar. This is why they pushed so hard with messaging about the superiority of Russia and Marxism-Leninism in the face of capitalism, even though we smoke-checked them in every category.
Same for China. China has always functioned with an authoritarian dynasty or dictator trying to manage the schism between the poverty-stricken interior and the coastal merchants and farmers. The existence of the US presents a massive threat to their political-economic system, which is now unraveling because they built their growth on exporting to the US and Europe.
Both Russia and China have been hell-bent on destroying the political-economic-military integrity of the US for quite some time. They are also long-time regional rivals with each other on the Eurasian continent, so there is no love between them, only suspicion and occasional opportunities.